| 2. | Secondly , based on the function requirement of usb device controller the system was divided into five modules , clock extracting , event detect , physical layer interface , media access controller , endpoint control layer and every module was designed in detail 其次,针对usb设备控制器的功能要求,将系统分为时钟提取、事件检测、物理层、介质访问层、端点控制层五个模块并对每个模块进行了详细设计。 |